Diarrhetic Shellfish Poisoning

Causative organisms: Dinophysis spp., Prorocentrum spp.*

Toxin implicated: Okadaic Acid and congeners; Dinophysistoxin-1, -2

Diarrhetic Shellfish Poisoning (DSP) produces gastrointestinal symptoms, usually beginning within 30 minutes to a few hours after consumption of toxic shellfish (Yasumoto and Murato, 1990). Although not fatal, the illness is characterized by incapacitating diarrhea, nausea, vomiting, and abdominal pain. Recovery usually occurs within three days, with or without medical treatment. Of the ~100 Dinophysis species, only 10 are known to produce diarrhetic toxins (okadaic acid and dinophysistoxins). Species of the morphologically similar "D. acuminata-complex" (D. acuminata, D. fortii and D. ovum) are most common in the US; however, toxin profiles and toxicity are highly variable, especially among strains (Reguera et al. 2014). Even at low cell densities (<103 cells·L−1), toxic Dinophysis spp. are a threat because they are concentrated by shellfish (mussels, clams, oysters, scallops). Cooking or freezing contaminated shellfish will not eliminate the toxins. Effects of chronic exposure are not well known; however, a possible association between exposure to DSP toxins and digestive cancers has been suggested (Cordier et al. 2000).

U.S. Finfish and Shellfish Vectors of DSP

Harmful Algal Species

Geographic Area

Affected Organisms*

Dinophysis acuminata

Dinophysis caudata

Dinophysis fortii

Dinophyisis norvegica

Dinophysis ovum

Prorocentrum lima+

NE Atlantic Coast

Washington

California

Gulf of Mexico

Mussels

Scallops

Clams

Oysters

*Found to contain algal toxins, or to be adversely affected by toxic or harmful marine algae.+Putative causative algae, but no DSP event attributed.